Old Components and Blow Holes

Are old components such as resistors and circuit breakers more likely to cause blow holes during wave soldering compared to new components?

D.B.

Expert Panel Responses

Blow holes are primarily the result of poor hole wall generation of the PWB and defective or insufficient plating thickness. Some components can outgas during assembly but again it is a function of poor plating quality regardless of age.

Bottom line, old components will not increase blow hole defects but you could have an increase in process voiding in the solder joints due to poor solderability of the older devices.

Gerard O'Brien
President
S T and S Testing and Analysis

Gerald O'Brien is Chairman of ANSI J-STD 003, and Co Chairman of IPC 4-14 Surface Finish Plating Committee. He is a key member of ANSI J-STD 002 and 311 G Committees Expert in Surface finish, Solderability issues and Failure analysis in the PWA, PWB and component fields.

I can certainly see old components causing wetting problems. If the wetting problems are spotty, localized issues and some happen to be near the fillet on the solder destination side, then they could look potentially look a little like there had been some outgassing.

If you feel that the defects are classic blowholes, then I'd say the source is very likely not the components but the PWB. The only way to be sure is to substitute a new lot of parts for a particular part that has been showing a lot of the defect in question, and see if the issue goes away. Now go back to the old parts. Does it come back? If you can turn it off and on, you know you are getting a handle on it.

Fritz Byle
Process Engineer
Astronautics

Fritz's career in electronics manufacturing has included diverse engineering roles including PWB fabrication, thick film print & fire, SMT and wave/selective solder process engineering, and electronics materials development and marketing. Fritz's educational background is in mechanical engineering with an emphasis on materials science. Design of Experiments (DoE) techniques have been an area of independent study. Fritz has published over a dozen papers at various industry conferences.

The best way to identify the cause is with a cross section of the circuit board joints exhibiting the problem.

Blow holes are the result of moisture/liquid trapped behind the plating of the plated through holes expanding to form gas, building enough pressure to break through the plated through hole wall and expanding into the solder joint. The cause is dull drill bits that did not give clean holes in the circuit board before plating.

Poor solderability components will contribute to poor barrel fill, however. This can be identified with a cross-section by seeing solder not wetting to the component lead within the plated through hole barrel.

Kay Parker
Technical Support Engineer
Indium Corporation

Kay Parker is a Technical Support Engineer based at Indium Corporation's headquarters in Clinton, N.Y. In this role she provides guidance and recommendations to customers related to process steps, equipment, techniques, and materials. She is also responsible for servicing the company's existing accounts and retaining new business.

Old components may lead to blow holes in wave soldering. As components age the oxide layer on the metal connectors grows. The chemical reaction between the flux and the metal oxide creates gasses. As the oxide level grows, the amount of gas generated increases. These gasses will escape from the solder and the escape route is typically a blow hole.

Tony Lentz
Field Applications
FCT Assembly

Tony has worked in the electronics industry since 1994. He worked as a process engineer at a circuit board manufacturer for 5 years. Since 1999, Tony has worked for FCT Companies as a laboratory manager, facility manager, and most recently a field application engineer. He has extensive experience doing research and development, quality control, and technical service with products used to manufacture and assemble printed circuit boards. He holds B.S. and M.B.S. degrees in Chemistry.

To be honest not normally as there should be nothing on the components to attract moisture in the first place. More than likely to be the PCB especially if HASL finished or Silver.

Greg York
Technical Sales Manager
BLT Circuit Services Ltd

Greg York has over thirty two years of service in Electronics industry. York has installed over 600 Lead Free Lines in Europe with Solder and flux systems as well as Technical Support on SMT lines and trouble shooting.

In general the older the component gets, the more the oxidation builds up on their leads. In the soldering process (reflow, selective soldering, wave soldering) the flux is applied to clean up this oxidation build up. There is no doubt that the older components are more likely to exhibit blow holes in the solder connections than the new components.

Georgian Simion
Engineering and Operations Management
Independent Consultant

Georgian Simion is an independent consultant with 20+ years in electronics manufacturing engineering and operations.
Contact me at georgiansimion@yahoo.com.

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